Evidence for expansion of the precuneus in human evolution

• Authors: Emiliano Bruner, Centro Nacional de Investigación sobre la Evolución Humana; Todd M Preuss, Emory University; Xu Chen, Emory University; James K Rilling, Emory University
• Journal Title: Brain Structure and Function
• Volume: Volume 222, Number 2
• Publisher: Springer Verlag (Germany) | 2017-03-01, Pages 1053-1060
• Type of Work: Article | Post-print: After Peer Review
• Publisher DOI: http://doi.org/10.1007/s00429-015-1172-y
• Subjects: Biology, Neuroscience; Anthropology, Medical and Forensic; Psychology, Behavioral
• Keywords: Science & Technology; Life Sciences & Biomedicine; Anatomy & Morphology; Neurosciences; Neurosciences & Neurology; Parietal lobes; Human evolution; Evolutionary neuroanatomy; Morphometrics; SUPERIOR PARIETAL CORTEX; CORTICAL SURFACE-AREA; HUMAN BRAIN EVOLUTION; DEFAULT-MODE; FUNCTIONAL CONNECTIVITY; ADULT HUMANS; GENUS HOMO; SHAPE; MONKEYS; ORGANIZATION

Abstract

The evolution of neurocranial morphology in Homo sapiens is characterized by bulging of the parietal region, a feature unique to our species. In modern humans, expansion of the parietal surface occurs during the first year of life, in a morphogenetic stage which is absent in chimpanzees and Neandertals. A similar variation in brain shape among living adult humans is associated with expansion of the precuneus. Using MRI-derived structural brain templates, we compare medial brain morphology between humans and chimpanzees through shape analysis and geometrical modeling. We find that the main spatial difference is a prominent expansion of the precuneus in our species, providing further evidence of evolutionary changes associated with this area. The precuneus is a major hub of brain organization, a central node of the default-mode network, and plays an essential role in visuospatial integration. Together, the comparative neuroanatomical and paleontological evidence suggest that precuneus expansion is a neurological specialization of H. sapiens that evolved in the last 150,000 years that may be associated with recent human cognitive specializations.